In an industrial plant provided with non-utility generation equipment, the whole electricity used in the plant is covered by both electricity by non-utility generation and electricity purchased from an electric company (contract electricity demand). In such an industrial plant, electricity which becomes necessary in the future (electricity demand) is predicted and the amount of electricity generated by non-utility generation (the amount of electricity by non-utility generation) is adjusted on the basis of the predicted value. That is, the total amount (i.e., a total value of the amount of electricity by non-utility generation and the amount of contract electricity demand) is set so that the amount of electricity supplied to the plant does not become lower than the above-described predicted value.
Patent Literature 1 below describes a system for predicting electricity demand. In the system described in Patent Literature 1, electricity demand is predicted on the basis of the amount of electricity used in a whole plant (an actual value).